Reproduction processes are known wherein positive-working photopolymerizable elements and negative-working photosensitive elements are exposed imagewise through an original forming nontacky and tacky image areas. Positive-working photopolymerizable elements are described in Chu and Cohen U.S. Pat. No. 3,649,268 and negative-working photosensitive elements are described in Cohen and Fan U.S. Pat. Nos. 4,174,216 and 4,191,572. The image is developed by toning with a suitable toner which desirably adheres only in the tacky image areas. Excess toner which may be present is removed from the nontacky image areas to provide, for example, an image which is a proof of the original or which can be used to transfer the image to another surface. Multilayer proofs such as surprint proofs can be made as well.
In view of the increasing importance of proof-making in the printing industry and the problems inherent therein, improved toners and applicators for applying these toners are desirable. Some recognized improvements in toners are those described in Chu and Manger U.S. Pat. No. 3,620,726, mixtures using these toners described in Gray U.S. Pat. No. 3,909,282 and the toners of Manger, Fickes and Long described in U.S. Pat. No. 4,215,193. From the early use of pads dipped in toners, improved toner applicators are the subject of Sandner U.S. Pat. No. 4,019,821 (hand operated toning) and Tobias U.S. Pat. No. 4,069,791 (automatic toning). Application of any of the above described toners as well as known prior art toners to tacky image areas of photosensitive elements has the problem that the toners are difficult to completely remove from the nontacky image areas of the said elements. Generally the excess toner is removed from the nontacky areas by means of mechanical action using a cloth, brush or other toner removal means. It is known that static is generated by rubbing dissimilar materials together. Depending on the particular film being toned and the toner removal means, the amount of static formed varies. For example, cleaning brushes closest to the film in the triboelectric table would be expected to generate a relatively low charge. Thus it would be expected that an acrylic brush would generate only a small charge with respect to an element that contains an acrylic compound in its photosensitive layer. The toner, however, can also generate a charge against the brush (or cleaning means) and the photosensitive element. If the toner, cleaning means and element have an identical place in the triboelectric table substantially no static charge would be generated. Such a system, while desirable, is not generally achieved. Despite the aforementioned disadvantage the cleaning of nontacky areas is desirable. In manual applications this is time consuming. Cleaning operation in a machine increases the cost thereof. After clean-up, some undesirable stain is usually present.
To overcome the above disadvantages it is desired to provide dry, nonelectroscopic toner particles which, when applied to imagewise exposed elements containing tacky and nontacky image areas, can be easily removed from the nontacky areas, e.g., without elaborate clean-up components in automatic toning machines. A further object is to provide such toners which substantially are nonstaining with respect to the nontacky areas.